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Thanks for the reply. I'd be grateful if you or someone else could address the second question I posed:
What should one do if he/she has to draw or paint the area (say - ruddy cheeks or dark spots on an apple) that has equal local value (in light) as adjacent shadow. Should one keep its value (in light) equal as the value of shadow?

Atelier Art Classes, Brisbane.

In case anyone reading is from Brisbane, just thought I should mention that Atelier Art Classes is flying me up in April for an intensive weekend colour theory workshop on the 16th-17th - details are on their website. In any case I strongly recommend that you check out the classes at their new studio. The teachers, including Ashtons wunderkind Ryan Daffurn, are all excellent, and they regularly conduct workshops with visiting artists. It's really great to see a school specializing in serious art instruction is now established in my home town.

i have read the dimension of color by brigg, and i say that is the most superb color theory i ever know.
and so sadly, i'm chinese indonesian, and my english is very bad... so i hav to read it several time just for one page. maybe now i'm lost nowhere.
the one that bothering me is the addictive and subtractive complimentary.... i just confuse when we used that... is the addictive for digital media, and subtractive is for traditional media? coz i find it hard to apply for my painting.

the other was the R/G vs Y/B formula... i know how the formula goes by looking in the attached SWF file, and to be honest that was incredible. but somehow i lost why and when to apply the formula.

would you please explain in more simply way for me? sorry of being annoying. but i really2 admire your color theory.

i always wanna paint a pale skin and low saturation skin, coz i saw the other artist can paint success of pale skin and low saturation environment and the painting doesnt strange and flat. but somehow i ended with very flat tone... what could be my problem?

maybe a link to my portfolio can explain what i mean
grapholic.deviantart.com.
rokai.

really looking forward to hear the solution from you briggs. the website of yours is really2 make my day.

WOW....Amazing

Totally amazing Mr Briggs, and I say that after reading only a particle of the whole of your research article. The key thing for me is that you have not only answered some very relative questions about color I have had since childhood, I am now 61 years of age, and I am learning some new aspects of color that make very good sense in my mind. I continue to read, a slow reader I am..... : )).

Thank you very much for the research and the article, amazing stuff for sure.

hello brigssy you invited me to post some points of trouble I have with color. I never worked alot with color always afraid to use it.

First of all I just have problems with color choice in general.
I think I have the biggest problem with which color to choose when it goes in to the shadow or light. I used to pick just a darker or lighter tone.

here is an example of a painting I made and post in the wip thread. I applied the suggestions and comments I got but I dont understand the why.

PS Zant, the only valid reason to make the dress a little bluer in the shadow is if the light influencing the shadow area is bluer, in which case you would need to make everything else bluer in the shadow by just the right amount to get a consistent visual effect. Another problem in your later versions is that you made the shadow colour less saturated, which makes it hard to see the material as being the same red object colour as it is in the light. There was nothing inherently wrong with your idea of just making the shadow colour darker (keeping the saturation the same), though you may have gone too dark in your first attempt (see below).

The most important component of colour is value, and that was your biggest problem. If you compare each of your shadow colours with the colour of the same material in the light, sometimes they are much darker, sometimes only a little darker, even comparing shadow surfaces facing exactly the same direction. You need to make these contrasts more consistent to create the effect of a consistent illumination.

I'll have a think about some practical exercises but in the meantime start working through The Dimensions of Colour if you haven't already. You may find the website easier going after you've read the James Gurney book you just ordered, as it's a very good first introduction to an informed approach to colour.

grapholic - very sorry I missed your questions when they came in. If you're still around I'll work on some answers as soon as I have some time.

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Hi Everyone! This is pretty much a copy paste from an Art Discussion post I made, but I was directed here by a kind user so here's to hoping someone can help me out!

As of late I've been feeling that everything I do in color turns out Bland and boring, and doesn't have the right sensitivity to color that I need as an artist. Are there any exercises I could do to improve my color selecting/usage abilities? Or does this just come with a LOT of practice.

On the same token, while using color I find I have a lot of issues with pushing Value also.

I just finished my first year of Art school, and I know basic principles of color, as well as the different types of Palettes. And I can look at a piece and discern the way they used the colors. But even still I have a really hard time with it. I've been reading a LOT of color books (Color and Light: Guide for the Realist Painter by James Gurney) and while they've really helped me understand certain lighting types and situation, Understanding and doing are two different things lol. Also, things from Observation I can get the colors fairly spot on, it's only when applying color to things from imagination where things get muddled.

I'll go ahead and post an example of where I'm at with Color, and the sensitivity I hope to achieve.

the one that bothering me is the addictive and subtractive complimentary.... i just confuse when we used that... is the addictive for digital media, and subtractive is for traditional media? coz i find it hard to apply for my painting.

The idea is to use the paint-mixing complementary for paint mixing, and the additive complementary for all questions having to do with vision. For example, to find the hue that is the most contrasting visually, use the additive complementary. Also, to know what colour an area will appear to move towards because of simultaneous contrast - > additive complementary. Apparent colour of the shadow of a coloured light source - > additive complementary. Colour to move towards to correct a colour cast in a photograph - > additive complementary.

Originally Posted by grapholic

the other was the R/G vs Y/B formula... i know how the formula goes by looking in the attached SWF file, and to be honest that was incredible. but somehow i lost why and when to apply the formula.

It's really just a better framework to have as your basic conception of colour, instead of the old idea that the basic colours are red, yellow and blue.
---------------------------------------------------------

Looking at your head studies on DA, I think you need to put in some variation in hue (redder and yellower parts) and chroma into your flesh colours. Take a look at this post:

If you think of the blue light as having lost some wavelengths, and the magenta paint as removing more, then it's really a kind of subtractive mixing. Subtractive mixing is not as predictable as additive mixing, because it depends on the exact distribution of wavelengths reflected by the paint as well as in the light. But you could definitely say that the paint would appear more bluish, or even blue if the colour of the light was saturated (pure) enough. But you would also expect that the perceived colour of the paint would not change as much as the actual wavelengths change, because our visual system would partially discount the colour of the light (colour constancy).

It's Doctor Briggs, by the way, but please call me David (or briggsy!).

Oh Dr David , Your THAT DUDE , THE Color and Light dude....I have always had you in my favorites : ).... Brilliant Methodical writing dude ....Thankyou from a Oil painter who sees Color for all its worth ....... Thumping!!!!

thank you very much Doctor Briggs! ^^
i think now i'm more understand now Doctor Briggs

so when the color of light is losing wavelength or let say "not blue enough" then it subtractive with the surface isn't it?
and if the light wavelength is 100% blue... then it's addictive with magenta?

so the second row is subtractive... then the third row is addictive? (if i'm not wrong)

sorry doctor... if my bad english is lost you somewhere... T^T

(in fact i'm reading your answer about ten times and open google translate for the meaning, i've trying hardest to totally understand what u said, though my english is very bad but i'm severely dying enough to learn it from you Doctor ^^)

Not quite, it's all subtractive mixing. The blue lights have some of the red and green parts of the spectrum missing, and the magenta paint then absorbs some more wavelengths, so the process can be classed as subtractive mixing.

The bottom row just shows squares copied out of the magenta row, against a grey background. These areas do not look as blue in the picture because of colour constancy.

Awwww Briggsy, you were in Brisbane earlier this year only a few blocks from where I live? Damn, wish I'd known. I have only just discovered the Atelier in Salisbury and they've still got your April workshop advertised for some reason. But yes, that's looking rather scrumptious. Are you going to come back for another round any time soon? And how long will it be until HuevalueChroma is back up?

Thanks for alerting me guys - looks like the site was intermittently down for three days or so due to an issue with EveryDNS. All fixed now, thanks once again to help from Ben Green (scibotic).

Sorry you missed the workshop Beeston! At least you've found the guys at Atelier - they're all awesome in different ways so make the most of them. Hopefully there'll be another two-day workshop in Brisbane at some stage; otherwise I run the full five-day workshop fairly regularly in Sydney, including one scheduled for the last week of this month if it gets a couple more students (anyone interested should let me know ASAP) and then again in January.

Constant saturation

Hi, thank you so much for the awesome site. Its amazing such valuable information is free. So much better than any of the books out there.

Just a question about the principle of uniform saturation. I noticed in a lot of photos where a white wall is lit by a light source that when you sample the colour of the wall in photoshop near the light it has a lower saturation than further away.

In the above the light source is on the left. The wall near the light has saturation of 18% and on the right the wall has saturation 27%. It's a bit hard to see in the image but the wall is white. Why has the saturation increased? Would this be because of ambient light? The light on the left is the only light source in the room. Wouldn't the ambient light be the same colour as the light source in this case? I assume the light is largely bouncing off other walls so wouldn't change much in hue.

The saturation of the subject's skin also increases on the right (away from the light). Because the light colour is determined using subtractive blending doesn't this suggests that the ambient light is warmer than the direct light on the left? (Because a warmer ambient light has relatively more R than B and G it would tend to make the skin redder thus more saturated).

You're not giving me much to go on, fawnha(!), but we need to consider the objects in the room as well as the walls. If the objects are mostly blue, the ambient light would be bluer than the main light; if they are mostly brown, the ambient light would be more yellow/orange, which is what we seem to see.

The real problem with Itten is not so much what is in the book as what isn't. Itten's conception of the scope of colour theory was strongly influenced by the Farbenlehre of Goethe (1810), which was a vitriolic and spectacularly misguided attack on the scientific approach to colour vision pioneered by Newton. Itten did at least admit that Newton was right about the spectrum, but otherwise, like Goethe, he ignored almost every development in our scientific understanding of colour after Newton. For example, like Goethe, he explained afterimages in terms of eye animism (the eye "requires" the complementary and "spontaneously generates" it if it isn't already present), not mentioning the fact that these phenomena had already been (at least partly) explained in terms of changing relative sensitivities of three receptors by Thomas Young in 1807 (and even earlier by Palmer).

A bit like Betty Edwards is for drawing, Itten might arguably be ok as a very first introduction to colour if you know nothing about the subject, but you'll want to get beyond that level as soon as possible. His simplistic eighteenth century colour wheel is ok to communicate the basic idea of the circular dimension of hue, but you'll find that it doesn't actually work for mixing colours on your computer or with your paints, and you'll need different hue circles for each of these situations. The colour sphere he adopts (originally published by Goethe's friend Runge in 1810) is a good introduction to the basic conception of three dimensions of colour forming a space, but again you'll want to go beyond it to the more sophisticated conceptions of Munsell or Arthur Pope to put the conception into practice.

It isn't really Itten's fault, but the continued widespread use of his book as the be all and end all of colour theory, nearly fifty years after it was written, and nearer a hundred after his ideas were formulated, is connected with a widespread and powerful tradition of ignorance in art teaching that refuses to engage with any scientific understanding of colour whatsoever. The scale of this great leap backwards is emphasized when you reflect that in the early twentieth century it was an art teacher, Albert Munsell, who invented the most widely used colour order system in the world.

Non-Linear Brightness and Luminance

As of now I still can't quiet understand one thing: The Conversion You did in Your two tables (for inclination angle and point source distance) from radiance to non-linear brightness.

How did You convert them?

But first let me see if I understood the meanings right now.

Brightness is a human perceptual value and non-linear, compared to and being the "percieved equivalent" of Luminance, which stands for the physical value of radiance. Two different words are used, to clearify that we see slightly different from what we would expect to see from the physical values. A grey surface with 18% radiance for example, appears mid-tone grey to us, although logic would tell us it should be darker according to a value from 0% - 100%. So Brightness is non-linearin relation toLuminance and it's physical radiance values.

Then You said Photoshop works with non-linear Brightness, in other words, the values from dark to light, dim to bright are graded according to human perception.

Then I found one formula You mention on Your site for converting from non-linear Brightness to linear Brightness (non-linear Brightness = linear Brightness * 0.45).
Does that mean linear Brightness = Luminance?
If not, could You please clarify the difference between these three terms?
And how to convert from Radiance to non-linear Brightness?

I'm a little bit confused now about Lightness too. I thought Lightness was the one perceptual equivalent of Brightness in the beginning. Since it's comparing to a white surface. Now I notice You say they are both perceptual values.

Luminance is the physical value of radiance, which can be physically, scientifically measured. (Okay, the others can to, but all basically in relation to this.)
So, Brightness is the perceptual value of light going from dim to bright. The perceptual value of luminance.
And Lightness is the perceptual value (the perception) of how bright any color seems to appear in relation to each other, including grey; generally compared to the "Lightness" of a white surface.

Linear = scaled proportional to light energyNonlinear = scaled proportional to human perceptionRadiance = light energy, scaled linearlyLuminance = light energy, scaled linearly, but with the visual effectiveness of the spectral components factored in (i.e. green wavelengths count for more than blue, because they look brighter to us at the same amount of energy) Brightness = luminance, scaled nonlinearlyLightness = brightness of an object relative to the perceived brightness of a white object in the same setting.

However Charles Poynton, whom I cite on the page where you got that formula, noted that so-called R, G and B "brightnesses" are sometimes given in linear units, and sometimes in nonlinear units, usually with no indication of which of the two is being used. "Linear brightness" of R,G or B would be the radiance (OR luminance) of each relative to their maximum radiance (OR luminance).

Today RGB brightness values seem to be dominantly of the nonlinear kind, though I have encountered the linear kind occasionally. In the two tables I used the inverse square law and cosine relationship respectively to get the fall off of light energy, and then converted this to nonlinear brightness (like the B in HSB) using the *0.45 formula.

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Today RGB brightness values seem to be dominantly of the nonlinear kind, though I have encountered the linear kind occasionally. In the two tables I used the inverse square law and cosine relationship respectively to get the fall off of light energy, and then converted this to nonlinear brightness (like the B in HSB) using the *0.45 formula.

This is where I feel like I am missing something.
In Your table we have for example 25% Radiance becoming 54% Brightness. (?)
However 25*0.45 = 11.25; and for the next one 11.11*0.45 = 4.9995.